The art of burying elongate members such as pipes or cables is well established and numerous apparatus and methods are known in the art. In many cases a trench cutting apparatus is used which, in a single operation, cuts a trench in the seabed and lays the elongate member in the newly formed trench. In some cases, the formation of the trench and the laying of the elongate member in the trench are performed as separate operations at different times and using different equipment.
Often in apparatus of this type, a so-called depressor is used during the stage of transferring the elongate member into the trench. The depressor acts to guide the elongate member to its intended location at the base or floor trench and also assists in ensuring that the elongate member is not bent further than its minimum radius of curvature which could cause damage to the elongate member.
Conventionally, apparatus for laying an elongate member in a trench is configured for laying the member in a substantially linear trench. The depressor is most often configured as a longitudinally extensive component which extends rearwardly from the apparatus and having a curved underside which acts to guide the elongate member to the base of the trench. Where the trench is linear, the rearward extent of the depressor causes no problems.
However, it is now more frequently required to lay an elongate member such as a pipe or cable in a non-linear (that is, curved) trench. In applications such as providing cables for offshore wind farms, the curve in the trench can have a small turning radius. The significant rearward extent of the depressor can become a significant problem in such curved trenches as, due to its length, the depressor may contact the walls of the trench and become wedged, or otherwise stuck or jammed in an particular location. Freeing the depressor from its jammed condition is often difficult and, at the very least, results in wasted time and money while attempts at rectification are made.
The present invention seeks to obviate or mitigate these problems.